Li₂O–ZnO–Co₃O₄–TiO₂ composite thin-film electrocatalyst for efficient water oxidation catalysis

ABSTRACT

Thin films of different Li₂O–ZnO–Co₃O₄–TiO₂ (LZCT) compositions were prepared and employed as electrocatalysts (i.e., anodes) to perform water oxidation reaction (WOR). The electrocatalytic activities of these thin films were compared with those exhibited by the sodium salt of cobalt phosphate (Na₂CoP₂O₇) (CP) thin-film electrocatalyst, which is a well-known water oxidation catalyst (WOC). These results suggest that the 10Li₂O–10ZnO–40Co₃O₄–40TiO₂ composition exhibits a better catalytic activity in terms of higher faradaic efficiency (>98%), lower over potentials (<400 mV), higher reaction stability (up to 30 continuous cyclic voltammetry (CV) cycles), and the rate of O₂ and H₂ gas evolution in terms of current density (about 1 mA/cm²) in comparison with those exhibited by CP thin-film electrocatalyst. Furthermore, these LZCT thin films exhibited very high specific surface area values and due to the unique microstructure of ZnCo₂O₄ phase evolved out of these LZCT compositions at a calcination temperature of 550°C for 30 min it has been found to be responsible for the higher specific surface area values measured for these thin-film compositions.

KEYWORDS:

• Cobalt
• electrocatalyst
• Na₂CoP₂O₇
• oxidation
• thin film
• titania
• water